Anionic surfactant, particularly, alkyl sulfate and alkyl polyoxyalkylene sulfate, is excellent in detergency and foaming power, and thus are widely used as cleansing ingredients for domestic or industrial use. An olefin sulfonate, particularly, an internal olefin sulfonate obtained with an internal olefin having a double bond inside an olefin chain, not at its end, as a raw material, has been reported as one of anionic surfactants.
Such an internal olefin sulfonate is generally obtained by sulfonating an internal olefin through reactions with a gaseous sulfur trioxide-containing gas, followed by neutralization and then hydrolysis of the resulting sulfonic acid. For example, Patent Documents 1 to 3 disclose improved production methods thereof.
The internal olefin sulfonate thus obtained is known to have good biodegradability or the like, but is still insufficient in a basic performance as a cleansing agent including foamability and foam quality, compared with general-purpose surfactants such as alkyl polyoxyalkylene sulfuric acid ester salt. Thus, further improvement in such a basic performance has been desired. As more people have concerned the water-saving or consumers' preferences have been diversified in recent years, the additional value of light foam quality and instantaneous foam dissipation property in addition to good foamability has also been required for use as a major activator in laundry detergents, dishwashing detergents, shampoos or the like. Specifically, it has been desired to develop a surfactant composition which allows foam to spread quickly by bringing about light foam quality derived from large bubbles and low bubble density and low foam viscosity during cleansing and also facilitates pleasant cleansing and rinsing in a short time by having instantaneous foam dissipation property quickly during rinsing. Such an additional value is useful for, for example, hair shampoos and body cleansers. As more people have a habit to wash their hair or bodies within a limited time before leaving the house after awakening or before going to bed, it tends to spend a considerable amount of time for spreading foam throughout their hair or thoroughly rinsing their hair. This is largely due to fine foam quality and high foam viscosity. If a surfactant composition having light foam quality and instantaneous foam dissipation property can be formulated in a shampoo, the resulting shampoo permits sufficient cleansing in a short time, and not only achieves pleasant cleansing but can bring about a refreshed feel after drying, leading to the realization of water-saving.
Patent Document 4 discloses a specific internal olefin sulfonic acid which is intended to impart the solubilizing ability, penetrating ability, and interfacial tension reducing ability as a cleansing component. It discloses that when it is used, for example, as a shampoo, it lathers well, and achieves an improved feel without friction. Patent Document 5 also describes a specific internal olefin sulfonate for the purpose of improving detergency, and discloses examples of application to shampoos, liquid soaps, and the like. Meanwhile, Patent Document 6 describes a promoter for recovering an oil using a surfactant containing a plurality of internal olefin sulfonates differing in the number of carbon atoms.
[Patent Document 1] JP-A-01-272564
[Patent Document 2] JP-A-61-134366
[Patent Document 3] JP-A-60-32759
[Patent Document 4] JP-A-2003-81935
[Patent Document 5] U.S. Pat. No. 5,078,916
[Patent Document 6] WO-A 2010/129051